1. Field of the Invention
The present invention relates to an on-vehicle navigation system, and particularly relates to an on-vehicle navigation system for performing route guidance for a vehicle to a destination along a recommended route.
2. Description of the Related Art
Conventionally, in an on-vehicle navigation system, after searching a recommended route from a current position to a destination by using a route calculation method such as Dijkstra's method, route guidance for a vehicle from the current position to the destination (in other words, route guidance) has been performed along the recommended route. Further, in this type of on-vehicle navigation system, before searching a recommended route, search conditions of a recommended route such as a route passing through an expressway can be set by user operation, for example, and a user thus was able to receive route guidance along a recommended route satisfying the set search conditions.
Freeways in big cities in the U.S. have roads equipped with a special lane, referred to as carpool lane, together with a normal lane. The carpool lane is a lane provided with the intent of removing a traffic jam, reducing exhaust gas, shortening commuting time or the like, and public buses, cars and motorcycles with two or more passengers (the specified number of passengers differing among states) can use the lane. However, hybrid cars can use the lane even in the case of one passenger if application is made to the motor vehicle official of a state government agency and permission is granted. If a vehicle that does not satisfy such requirements enters the carpool lane, the driver is fined for the violation. Legal advancing from the normal lane to the carpool lane is authorized only from a predetermined advancing authorized section (in other words, entrance), and legal exiting to the normal lane is authorized only from a predetermined exiting authorized section (in other words, an exit). Note that the exiting authorized section matches the advancing authorized section in many cases in such a carpool lane.
Some on-vehicle navigation systems capable of previously setting whether such a carpool lane should be used or not as a search condition of a recommended route have conventionally been suggested (Japanese Patent Laid-open No. 131085/2000, for example). However, there has conventionally been a case where the user deviated from a recommended route including the carpool lane to drive on the normal lane due to various circumstances. In such a case, even though he/she did not drive in the carpool lane, guidance of an exiting authorized section of carpool lane was provided as part of route guidance along the recommended route, and it caused a problem that users became confused or irritated.
Conversely, there has been a case where the user deviated from a recommended route not including the carpool lane to drive in the carpool lane. In such a case, the user conventionally had to confirm the exiting authorized section for returning to the recommended route without being unable to depend on the route guidance of an on-vehicle navigation system. However, since it is difficult to find the exiting authorized section of carpool lane in many cases, there has been a problem that the user could miss a chance of returning to the recommended route by choosing a wrong exiting authorized section.